1. Field of the Invention
The present invention relates to a impression composition, in particular, to a impression composition having good hydrophilic nature and a small cure shrinkage.
2. Description of the Prior Art
Heretofore, for various kinds of impression materials including dental impression materials, materials containing as a main ingredient a polyether (Japanese preexamination Patent Publication (KOKAI) No. 55538/1986), polysulfide, and a silicone have been used.
However, of the above materials, polyethers have hydrophilic nature, but has the disadvantage that its cure shrinkage is too large. The polysulfide has a strong unpleasant smell. Although the silicone has a good impression performance, it has poor hydrophilic nature; hence it has the disadvantage that when used for dental purposes, impression performance at portions wet with saliva or blood is worse.
Therefore, it has been proposed to impart hydrophilic nature to silicone materials by adding a polyether modified siloxane or a fluorine-containing surfactant. However, this may cause blooming of the additive or liquid separation during processing on a molding device.